Once completed, the Grand Ethiopian Renaissance Dam will be nearly twice as tall as the Statue of Liberty and as wide as the Brooklyn Bridge is long. The reservoir behind it is roughly the size of London. Sitting on the Blue Nile, the main tributary of the Nile river, the dam is the largest hydro-electric project in Africa. Soon it will produce 6,000 megawatts of electricity, more than double Ethiopia’s output today. With a little co-operation between Ethiopia and its downstream neighbours, Egypt and Sudan, the dam could be a boon for the whole region.